1. Environmental Science: Toward a Sustainable Future
The Atmosphere: Climate, Climate Change, and Ozone Depletion and Atmospheric Pollution

2. The Atmosphere: Climate, Climate Change, and Ozone Depletion
Atmosphere and weather
Climate
Global climate change
Response to climate change
Depletion of the ozone layer

3. Atmosphere and Weather
Atmospheric structure
Weather: The day-to-day variations in temperature, air pressure, wind, humidity, and precipitation mediated by the atmosphere in a given region.

4. Atmospheric Structure

5. Weather: Solar Energy Balance
Most solar energy absorbed by atmosphere,
oceans, and land

6. Climate
Defined as the average trend in temperature and rainfall that produces a unique assemblage of plants and animals

7. Climates in the Past

8. Global Climate Change The Earth as a greenhouse The greenhouse gases
Evidence of climate change
Anthropogenic: pollutants and other forms of impacts on naturals environments that can be traced back to human activities

9. The Earth as a Greenhouse

10. Factors Affecting Global Temperatures
Cloud cover: cooling
Changes in Sun’s intensity: cooling or warming (11-year sunspot cycle)
Seems low sunspot, lower temp.
Volcanic activity: cooling
Sulfate aerosols: cooling

11. Greenhouse Gases: CO2 Emissions from Fossil Fuel Burning
35% higher than before industrial revolution
Oceans = CO2 sinks (oceanic absorption)
Forests = CO2 source when burned
24 billion metric tons CO2 added each year

12. Other Greenhouse Gases and Sources
Water vapor
Methane
Nitrous oxide
CFCs and other halocarbons
Hydrologic cycle
Animal husbandry
Chemical fertilizers*
Refrigerants*
* = Long residence times and contribute to
ozone depletion

13. Atmospheric CO2 Concentrations

15. Global Surface Temperatures

16. Global Carbon Cycle
Billion metric tons

17. Impacts of Global Warming
Melting of polar ice caps and glaciers
Flooding of coastal areas due sea levels rising
Thermal expansion of oceans
Ocean currents shifting (ENSO)

18. Impacts of Global Warming
Alteration of rainfall patterns
Deserts becoming farmland and farmland becoming deserts
Significant losses in crop yields

19. Evidences of Climatic Change
17 of the hottest years on record have occurred since 1980
Wide-scale recession of glaciers
Sea level rising
Predicted mean global temperature change
by 2100 is between 1.5 and 4.5oC

20. Depletion of Ozone Layer
Radiation and importance of the shield
Formation and breakdown of the shield
Coming to grips with ozone depletion

21. Good Ozone!
Bad Ozone!

22. Radiation and Importance of the Shield
Stratosphere provides 99% shield from UV radiation to troposphere
Skin cancer (700,000 new cases each year)
Premature skin aging
Eye damage
Cataracts
Blindness

23. Formation of the Ozone Shield
Reaction #1: UV light + O2
O + O
Reaction #2: Free O + O2 O3
Reaction #3: Free O + O3
O2 + O2
Reaction #4: UV light + O3
O + O2

24. Chlorofluorocarbons (CFCs)
Organic molecules in which both chlorine and fluorine atoms replace some of the hydrogen atoms
Sources:
refrigerators and air conditioners
production of plastic foam
cleaner for electronic parts
pressurizing agent in aerosol cans

25. Breakdown of Ozone Shield
Reaction #5: CFCl3 + UV
Cl + CFCl2
Reaction #6: Cl + O3
ClO + O2
Reaction #7: ClO + ClO
2 Cl + O2
Which reaction releases Cl from CFCs?
Which reaction generates more Cl?
Chlorine is a catalyst that destroys
the production of ________?

26. Montreal Protocol
1987 – scale back CFC production by 50% by 2000

27. Coming to Grips with Ozone Depletion: Montreal Protocol
1990 – amendment to completely phase out ozone-destroying chemicals by 2000
1992 – amendment to completely phase out ozone-destroying chemicals by 1996
Why the rush?

28. Ozone Hole: 11 million sq.mi.
TOMS: Total Ozone Mapping Spectrometer
Dobson Unit (DU): a measure of the total amount of ozone in a column of the atmosphere (total column ozone) from ground level to the top of the atmosphere, based on analysis of absorbed ultraviolet light. The number of Dobson units corresponds directly with the “thickness” of the ozone layer. While measurements vary widely according to time and place, a typical reading for a healthy polar ozone layer might be in the Dobson unit range.
Ozone Hole: 11 million sq.mi.

29. 1997 The ozone hole is indicated by ozone values less than 220 Dobson Units (the violet colors).

30. The Clean Air Act of 1990: Title IV
Restricts production, use, emissions, and disposal of ozone-depleting chemicals
Regulates the servicing of refrigeration and air-conditioning units
“Protecting Stratospheric Ozone”

31. Pollutants and Atmospheric Cleansing
Air pollutants: gases and aerosols in the atmosphere that have harmful effects
Level of air pollution determined by:
The amount of pollutants entering the air
The amount of space into which the pollutants dispersed
Mechanisms that remove pollutants from the air (i.e. wind speed & direction, precipitation)

32. The Appearance of Smog
Smoke + Fog = Smog

33. Impacts of Smog: Temperature Inversion

34. Air Pollution Effects Adversely affects human health
Damages crops and forests
Highly corrosive

35. Major Air Pollutants and Their Sources
Suspended particulate matter
Volatile organic compounds (VOCs)
Carbon monoxide
Nitrogen oxides
Sulfur oxides
Heavy metals
Ozone
Air toxics

36. Major Air Pollutant Sources

37. Major Air Pollutants: Primary (see next slide)
Primary pollutants derived directly from burning fuels and wastes
Particulates (dust, fuel combustion)
Hydrocarbons (CFCs)
Carbon monoxide (looks like O2)
Nitrogen oxides (industries)
Sulfur dioxides (contributes to acid rain)

39. Major Pollutants: Secondary (see next slide)
Secondary air pollutants derive from reactions that occur between primary pollutants and other atmospheric chemicals
Ozone
PANs (peroxyacetyl nitrates)
Acids: sulfuric and nitric

41. Major Sources of SO2 Emitters
All sources are coal-burning power plants

42. Impacts of Air Pollutants on Human Health
Chronic: gradual deterioration of a variety of physiological functions over a period of years; Ex: lead poisoning – leads to neurological damage
Acute: life-threatening reactions within a period of hours or days; Ex: asthmatics or elderly
Carcinogenic: cancer-causing; Ex: lung cancer

43. Impacts of Air Pollutants on the Environment
Plants
Necrotic: kills plant cells
Chlorotic: destroys chlorophyll, reducing photosynthesis
Increases susceptibility to disease and pests
Ozone most serious pollutant

44. Ozone Impact on Crop Yields

45. Impacts of Air Pollutants on the Environment
Forests
Leaching of nutrients
Release of aluminum into solution
Rapid changes in soil chemistry
Reduced growth and diebacks of plants and animals
Increased soil erosion, flooding, sedimentation in waterways

46. Impacts of Air Pollutants on the Environment
Materials
Loss of color
Oxidation
Corrosion
Decreased real estate values (degrades building materials)

47. Effects of Acid Deposition
Alteration of plant and animal reproduction
Leaching of other toxic elements, e.g., aluminum
Eutrophic to oligotrophic conditions
Total loss of biota from aquatic ecosystems
Alterations of food chains

48. Bringing Air Pollution under Control
Clean Air Act identifies most widespread pollutants: e.g., particulates, SO, CO, NO, lead = criteria pollutants
National Ambient Air Quality Standards (NAAQS) set levels that protect environmental and human health

49. Bringing Air Pollution under Control
NAAQS: also set national ambient air quality standards
National Emission Standards for Hazardous Air Pollutants set national emission standards for hazardous air pollutants

50. Title IV Clean Air Act 1990 Title X Clean Air Act 1990
Reduce SO emissions 50% below 1980 levels
Improve methods of reducing SO emissions
Allow emissions allowances and trading
Emissions purchases
Reduce NO emissions
Title X Clean Air Act 1990
Addresses acid rain deposition

51. Industry’s Response to Clean Air Act - 1990
Fuel switching
Scrubbers
Emissions allowance trading
Using low-sulfur coals